On 19.05.15 10:38, Stefan Podkowinski wrote:
Multiple inserts for the same partition key within a batch will be
consolidated into a single row update operation (since 2.0.6, #6737
<https://issues.apache.org/jira/browse/CASSANDRA-6737>). Ie. you get
the same row level isolation
<http://www.datastax.com/dev/blog/row-level-isolation> guarantees as
any single write operation on that key.
This is exactly what I need, thanks for clarifying and sharing the link(s).
*Von:*Martin Krasser [mailto:krass...@googlemail.com]
*Gesendet:* Montag, 18. Mai 2015 12:32
*An:* user@cassandra.apache.org
*Betreff:* Batch isolation within a single partition
Hello,
I have an application that inserts multiple rows within a single
partition (= all rows share the same partition key) using a BATCH
statement. Is it possible that other clients can partially read that
batch or is the batch application isolated i.e. other clients can only
read all rows of that batch or none of them?
I understand that a BATCH update to multiple partitions is not
isolated but I'm not sure if this is also the case for a single partition:
- The article Atomic batches in Cassandra 1.2
<http://www.datastax.com/dev/blog/atomic-batches-in-cassandra-1-2>
says that /"... we mean atomic in the database sense that if any part
of the batch succeeds, all of it will. No other guarantees are
implied; in particular, there is no isolation"/.
- On the other hand, the CQL BATCH
<https://cassandra.apache.org/doc/cql3/CQL.html#batchStmt> docs at
cassandra.apache.org mention that /"/ /... the [batch] operations are
still only isolated within a single partition"/ which is a clear
statement but doesn't it contradict the previous and the next one?
- The CQL BATCH
<http://docs.datastax.com/en/cql/3.1/cql/cql_reference/batch_r.html>
docs at docs.datastax.com mention that /"... there is no batch
isolation. Clients are able to read the first updated rows from the
batch, while other rows are still being updated on the server.
However, transactional row updates within a partition key are
isolated: clients cannot read a partial update"/. Also, what does
/"transactional row updates"/ mean in this context? A lightweight
transaction? Something else?
Thanks for any help,
Martin
--
Martin Krasser
blog: http://krasserm.github.io
code: http://github.com/krasserm
twitter: http://twitter.com/mrt1nz
